<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			.son{
				background: black;
			}
		</style>
		<link rel="stylesheet" type="text/css" href="css.css"/>
	</head>
	<body>
		<div id="baba">
			<div class="son one">大儿子</div>
			<div class="son">二儿子</div>
			<div style="color:red ;" class="son">三儿子</div>
		</div>
	</body>
</html>
